The investigators are proposing to take the next logical step in the development and application of EPR spectroscopy to animal model physiology and eventually to human pathophysiology: the development of apparatus that can be moved to other laboratories, clinics, or operating rooms where spectroscopic measurements are needed. The proposal will involve the development of 1) a moveable system weighing less than 660 lbs with a large gap magnet; 2) a compact modularized bridge; and 3) a user friendly computer controller/interface allowing precalibrated specimens to report the physiologic parameter to be measured in familiar units.